1. Field of the Invention
The present invention relates to the field of display technology, and in particular to an OLED (Organic Light-Emitting Diode) packaging method and structure.
2. The Related Arts
In the field of display technology, flat panel display technology (such as liquid crystal display (LCD) and Organic Light Emitting Diode (OLED)) has been gradually replacing cathode ray tube (CRT) displays. Flat light source technology is a novel light source, of which the development of techniques thereof has approached the level of commercialized mass production. In the flat panel display and flat light source technology, bonding of two parallel glass panels is an important technique of which the packaging effect directly affects the device performance.
Ultraviolet (UV) curing is the earliest and most commonly used technique for LCD/OLED packaging and has the following advantages: involving the use of no or a small amount of solvent so as to reduce environmental pollution caused by the solvent; consuming less energy, being curable in a low temperature and applicable to heat sensitive materials; and high curing speed and high efficiency, allowing for use in high speed manufacturing lines and having small footprint of the curing facility. However, UV resin is an organic material, which, after being cured, has relatively large gaps among the molecules thereof, allowing for easy penetration of moisture and oxygen through the medium to reach the internal sealed area. Thus, it better suits for applications in fields that are not sensitive to moisture and oxygen, such as LCD. However, OLED devices are very sensitive to moisture and oxygen and it is commonly to arrange a desiccant in the interior of a device when UV packaging is adopted in order to reduce the moisture that reaches the internal sealed area for extension of the lifespan of the OLED device.
FIG. 1 illustrates a commonly used OLED packaging method, in which a recess is first formed in a package cover 400 and a desiccant 300 is disposed in the recess of the cover 400, followed by application of frame resin 500, and finally the package cover 400 and an OLED substrate 100 are laminated and packaged together. FIG. 2 shows an other commonly used OLED packaging method, in which a layer of desiccant 300′ is directly coated on a package cover 400′, followed by application of a frame resin 500′ and finally, the package cover 400′ and an OLED substrate 100′ are laminated and packaged together. However, these two methods are both not suitable for top lighting arrangements (for light being not allowed to project out in the direction of the package cover), because light transmittance gets deteriorated after the desiccant absorbs moisture. Further, the moisture, after penetrating through the frame resin, may move around in the sealed area and may be absorbed by the desiccant or get attached to a surface of the OLED device. This may cause damages of the OLED device at the time when the moisture enters the sealed area.